﻿body {
	margin:0;
	padding:0;
}
#box {
	width:100px;
	height:100px;
	position:absolute;
	top:100px;
	left:100px;
	background:red;
	filter:alpha(opacity=30);
	opacity:0.3;
}
#aaa {
	width:300px;
	height:500px;
	background:#ccc;
}